Infective endocarditis caused by Nocardia nova: A case report and literature review of nocardial endocarditis

Metagenomic analysis of oral plaques and aortic valve tissues reveals oral bacteria associated with aortic stenosis

OBJECTIVES

Bacteria derived from the oral cavity enter the bloodstream and cause the onset of various systemic diseases, including heart valve disease. However, information on the oral bacteria involved in aortic stenosis is limited.

MATERIALS AND METHODS

We comprehensively analyzed the microbiota in aortic valve tissues collected from aortic stenosis patients using metagenomic sequencing and investigated the relationships between the valve microbiota, the oral microbiota, and oral cavity conditions.

RESULTS

Metagenomic analysis revealed the presence of 629 bacterial species in five oral plaques and 15 aortic valve clinical specimens. Patients were classified into two groups (A and B) according to their aortic valve microbiota composition using principal coordinate analysis. Examination of the oral conditions of the patients showed no difference in the decayed/missing/filled teeth index. Bacteria in group B tend to be associated with severe disease, and the number of bacteria on the dorsum of the tongue and the positive rate of bleeding during probing were significantly higher in this group than in group A. The pathophysiology of aortic stenosis may be related to the presence of oral bacteria such as Streptococcus oralis and Streptococcus sanguinis following bacteremia.

CONCLUSIONS

Systemic inflammation in severe periodontitis may be driven by the oral microbiota, supporting the indirect (inflammatory) association between oral bacteria and aortic stenosis.

CLINICAL RELEVANCE

Appropriate oral hygiene management may contribute to the prevention and treatment of aortic stenosis.

Native Valve Endocarditis Caused by Nocardia asteroides in an Immunocompetent Host: A Case Report and a Review of the Literature

Nocardia species are a rare cause of infective endocarditis (IE). We describe a case of native valve endocarditis caused by Nocardia asteroides in a 38-year-old Hispanic male with no apparent environmental exposures or risk factors for IE. Transesophageal echocardiography revealed severe mitral regurgitation, prompting emergent replacement of the valve. Nocardia asteroides were isolated from the tissue culture of the mitral valve. MRI of the brain also demonstrated innumerable micronodular intra-axial lesions throughout the brain, consistent with disseminated nocardiosis. The patient was treated with intravenous trimethoprim/sulfamethoxazole, meropenem, and amikacin for a six-week course, followed by oral trimethoprim/sulfamethoxazole and minocycline for 12 months. Follow-up after 18 months revealed no evidence of relapse. Although several cases of endocarditis due to Nocardia asteroides have been reported in immunocompromised hosts, to the best of our knowledge we believe the present case is the first to describe native valve endocarditis by Nocardia asteroides in an immunocompetent host with no apparent risk factors for IE.

Infective endocarditis by Nocardia species: a systematic review

Nocardiosis, is a potentially life-threatening disease, especially in immunocompromised individuals where it manifests as a disseminated disease. Infective Endocarditis (IE) is a rare disease with significant morbidity and mortality. Importantly, even though there are scarce data of IE by Nocardia spp. in the literature, a review adequately summarizing systematically all available evidence on the topic is lacking. The aim of this study was to systematically review all cases of IE by Nocardia spp. and describe the epidemiology, microbiology, clinical characteristics, treatment and outcomes of this infection. A systematic review of PubMed, Scopus and Cochrane library (through 7 December 2021) for studies providing epidemiological, clinical, microbiological as well as treatment data and outcomes of patients with IE by Nocardia spp. was performed. A total of 25 studies providing data for 26 patients were included. A prosthetic valve was present in 30.8%, while the most common microorganism was N. asteroides. Aortic valve was the most commonly infected intracardiac site, followed by the mitral valve. Diagnosis was most commonly performed with transthoracic echocardiography, while the diagnosis was made at autopsy in 11.5%. Co-trimoxazole, aminoglycosides and carbapenems were the most commonly used antimicrobials. Clinical cure was noted in 73.1%, while mortality was 26.9%. This systematic review thoroughly describes IE by Nocardia and provides information on epidemiology, clinical presentation, treatment and outcomes.

Disseminated Nocardia farcinica involves the spinal cord: a case report and review of the literature

Background

Nocardia is a relatively rare opportunistic pathogenic bacteria group, commonly seen in patients with immunocompromised or defective immune system. It can affect multiple organs of the body and cause disseminated infection, among which most occurs in the lung, secondly in the nervous system, soft tissues, rare in the spinal cord and pituitary. No case has been reported involving lung, spinal cord, skin and pituitary gland at the same time.

Case presentation

We report a 55-year-old female with Nocardia infection involving the lung, skin, spinal cord, and pituitary gland. The patient underwent a full set of imaging examinations and showed typical imaging findings. Chest computed tomography (CT) showed multiple nodules with cavities in the lungs. The magnetic resonance imaging (MRI) of the vertebral body showed abnormal signal of the entire spinal cord with cavity formation and ring enhancement. The subcutaneous nodules of the abdomen were punctured under ultrasound. Through the etiological tissue culture of subcutaneous nodules and the second generation sequencing of cerebrospinal fluid, the diagnosis was finally confirmed.

Conclusion

Disseminated Nocardiosis is an uncommon disease. This article will report a rare case of disseminated Nocardiosis simultaneously involving the lung, spinal cord, subcutaneous soft tissue and pituitary gland, especially with neuropathy as the initial symptom. Imaging is helpful for the early diagnosis of the disease and pathological and microbiological examinations are helpful for its confirming.